(NaturalNews) Infant formula may be contaminated with arsenic, suggests a study conducted by researchers from Dartmouth College and published in the journal Environmental Health Perspectives on February 23.

The study found that breastfed babies had lower levels of arsenic in their urine than formula-fed babies, even in areas where there was little arsenic contamination of local water supplies.

"This study's results highlight that breastfeeding can reduce arsenic exposure even at the relatively low levels of arsenic typically experienced in the United States," co-lead author Kathryn Cottingham said. "This is an important public health benefit of breastfeeding."

Arsenic is a naturally occurring element that is a potent poison and can lead to serious health consequences even in small doses. It has been linked with hormone disruption, cancer and other diseases, and early childhood exposure has been connected with lower birth weight, infant death, and lowered cognitive function.

But prior studies have shown that even when mothers are exposed to high levels of arsenic, breast milk does not contain high levels of the poison. Instead, the body seems to actively filter it out of the milk.

70 percent of arsenic comes from formula

The Dartmouth researchers analyzed urine from 72 six-week old babies born to mothers who had been recruited in January 2009 while pregnant. Seventy percent of the babies were being exclusively breastfed, 13 percent exclusively formula fed and 17 percent being fed on a combination. The highest arsenic levels were found among formula-fed infants, and the lowest among breastfed infants.

The study was conducted in New Hampshire, where 40 percent of the public's drinking water comes from private wells. Unlike with public water supplies, there is no regulation of arsenic levels in private wells. Thus, the arsenic exposure in the formula-fed infants might be expected to come from well water used to reconstitute powdered formula.

Yet after sampling the participants' water supplies and reviewing published data on arsenic levels in area wells, the researchers concluded that an astonishing 70 percent of the arsenic detected in the study actually came from the powdered formula itself.

"In conclusion, our findings suggest that breastfed infants have lower exposure to arsenic than formula-fed infants, even when drinking water arsenic concentrations are low," the researchers wrote.

Although breastfeeding rates in the study were high, this is because the infants were tested at such a young age.

"We predict that population-wide arsenic exposure will increase during the second part of the first year of life as the prevalence of formula-feeding increases," co-lead author Courtney Carignan said.

How to protect your child

In the rare cases where a woman absolutely must formula feed, Cottingham suggests testing the local water supplies to make sure that it is not contaminated with arsenic. Yet this would not protect against contamination in the formula itself.

A healthier option all around, when possible, would be to get human milk from a certified milk bank.

Even after babies or young children have weaned, they remain at risk for arsenic exposure. In a June 2014 report, the European Society for Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) Committee on Nutrition warned that widespread arsenic contamination of rice poses a particular risk to infants and young children, who are often fed rice-based cereals and beverages. Rice ingredients, such as starch, are also commonly added to infant foods.

"That contributes to high exposure of infants and young children to inorganic arsenic which is two to three times higher than in adults," the report notes.

The report notes that neither the United States nor the European Union currently regulates the arsenic content of foods, not even foods meant for infants.